Question 1056365
===3x-8
x-7/3x^2-29x+56
==3x^2-21x
change sign and add
======-8x+56
======-8x+56
change signs and add.  It is 0.
(x-7)(3x-8)
x=8/3
f(8/3) should be 0
3*(64/9)-29(8/3)+56=(192/9)-(696/9)+(504/9)=0
=====================
F(6)=6^3-4(6^2)-72+15=216-144-57
=15. The graph shows when x=6, y=15 by inspection.
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{{{graph(300,300,-10,10,-10,20,x^3-4x^2-12x+15)}}}